In distributing power in an electronic system, such as a shelf with plug-in cards, it is often necessary or desirable to control the voltage distribution to within specific tolerances throughout the system. For example, it might be necessary in some circumstances to distribute the voltage with a ±1% tolerance. This means that the voltage at a given point in the system should be within ±1% of the desired voltage. There are various reasons for requiring these tolerances such as power requirements of individual cards.
In systems with plug-in cards this degree of control is often obtained by placing regulator circuits on each card. The regulators are able to control the voltage to within the desired degree of accuracy. However, reproducing the circuitry for multiple cards is more expensive than using a single converter. In addition, reproducing the multiple circuits takes up extra space on the cards and in the shelf.
One method of regulating the voltage without placing regulator circuits on each card is to use power and ground planes in the motherboard to which the cards are attached. However, the motherboard contains many pin holes or vias to couple to and transfer signals between the cards. Connectors for power and ground either require the addition of more vias or the use of vias already on the card. This creates a number of problems. First, space on the motherboard is often limited. The use of vias for power and ground further limits the vias available for signal transfer. Second, the many vias in the motherboard increases the resistance in the motherboard. This increase in resistance creates problems with excess voltage drops. It, therefore, becomes difficult to regulate the voltage to within the needed tolerances. Third, the conductor layer thickness is limited in the motherboard for practical reasons. The limited thickness also increases the resistance in the motherboard.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a more efficient system of distributing power.